East African Journal of Veterinary and Animal Sciences (2018) Volume 2 (1): 1-10 Prevalence of Bovine Mastitis, Risk Factors and major Causative Agents in West Hararghe Zone, East Ethiopia Ketema Boggale, Bekele Birru*, Kifle Nigusu, and Shimalis Asras Hirna Regional Veterinary Laboratory, P.O. Box 36, Oromia Regional State, Ethiopia Abstract: A cross-sectional study was conducted from October 2009 to March 2010 in Boke, Darolebu, Kuni, Mieso and Tulo districts to estimate the prevalence of bovine mastitis, identify associated risk factors and isolate the predominant bacterial agents. A total of 1019 lactating cows were examined clinically and using California Mastitis Test (CMT) for subclinical mastitis. Standard bacteriological techniques were employed to isolate the bacterial agents. A total of 393 (38.6%) cows were positive for both clinical and subclinical mastitis. Among the risk factors, age, parity, and lactation stages were not significantly (p>0.05) associated with prevalence of mastitis. However, hygienic status of animals was associated with the occurrence of mastitis (p<0.05). Both contagious and environmental bacteria were isolated from milk samples collected from mastitic cows. The predominant bacteria isolate was Staphylococcus aureus with proportion of 14.1% followed by S. agalactiae with isolation proportion of 13.2%. E. coli and S. intermedius were the third predominant isolates with a rate of 10.9% for each. Among the seven antibiotics tested, gentamycin, amoxicillin, oxytetracycline, ampicillin, and cloxacillin were effective, whereas streptomycin and penicillin showed poor efficacy. The study revealed that mastitis is significant problem of dairy cows in the study areas. Hence, awareness creation among dairy farmers should be made about the impact of the disease; and training on hygienic milking practice and treating of subclinically infected cows should be given. Keywords: California mastitis test, Clinical mastitis, Risk factors, Subclinical mastitis Introduction (Mungube et al., 2004). Mastitis as a disease, especially Ethiopia has the largest livestock population compared the subclinical form, has received little attention in the to other African countries and cows represent the country and efforts have only been concentrated on the largest population of cattle of the country (CSA, 2009). treatment of clinical cases (Girma, 2001). The Milk produced from these animals provides an pathogens responsible for causing mastitis are broadly important dietary source for the majority of rural as classified into contagious and environmental agents well as considerable number of the urban and peri- (Quinn et al., 2002). The common microorganisms urban population. However, milk production often responsible for mastitis and spoilage of milk includes does not satisfy the country’s population requirement. Staphylococcus aureus, Streptococcus agalactiae, Corynebacterium According to the reports of FAO (2015a & b), the total bovis, Mycoplasma species, and Streptococcus uberis (Erskine, annual national raw milk production in Ethiopia ranges 2001), coliforms (Escherichia coli, Klebsiella species and from 797,900 to 1,197,500 metric tons equivalents of Enterobacter aerogenes), Serratia, Pseudomonas, Proteus which 85 to 89 % is contributed by cattle. However, species, environmental Streptococci, and Enterobacter this amount is by far below the national demand for species (Quinn et al., 2002). milk and milk products, showing the considerable In Ethiopia, the available information indicates that potential for increasing small holder income and bovine mastitis is one of the most frequently employment opportunities across the dairy production encountered and prevalent diseases of dairy cows value chain. causing economic loss as a result of reduced milk yield, Mastitis is among important health problems in dairy discarded milk, and early culling of productive cows cattle and considered as one of the most important (Fekadu, 1995; Mekonnen et al., 2005). The reported threats affecting the dairy industry throughout the prevalence of mastitis in different parts of Ethiopia country (Biffa et al., 2005). Mastitis is an inflammation ranges from 1.2% to 21.5% (Kassa et al., 1999; Lemma of the mammary gland and udder tissue that usually et al., 2001; Mungube, 2001; Workineh et al., 2002; occurs as an immune response to bacterial invasion of Kerro and Tareke, 2003). the teat canal by variety of bacterial sources present on Across the globe, various reports indicated that S. the farm, and can also occur as a result of chemical, aureus showed resistance to penicillin. Previous study in mechanical and thermal injury to the udder (Wellenberg Italy (Gentilini et al., 2000), Argentina (Gianneechini et et al., 2002; Radostits et al., 2007). It is mostly a result of al., 2002), and Uruguay (Pitkala et al., 2004) reported a combined interplay among exposure to microbes, cow resistance rate of 47%, 40%, and 47%, respectively. In defence mechanisms and environmental risk factors Ethiopia, S. aureus isolates were highly resistant to (Suriyasathaporn et al., 2000). Mastitis is a management clindamycin (73.8%), bacitracin (72.1%) and related disease whose prevention and control depends vancomycin (70.5%) (Shimelis, 2014). The high among other factors on good management practices incidence of resistant bacteria might be due to ___________________________________________ *Corresponding Author. E-mail: [email protected] ©Haramaya University, 2018 ISSN 2616-8804 (Print) Ketema et al. East African Journal of Veterinary and Animal Sciences 2 (1): 1-10 indiscriminate use of antibiotics and intra-mammary years), adults (> 6 to 10 years), and old (> 10 years). preparations containing combinations or single broad- Parity was categorized as few (1- 3 calves), moderate (4- spectrum antibiotics (Pitkala et al., 2007). Edward et al. 7 calves), and many (> 7calves) (Berhanu et al., 2010). (2002) suggested a possible development of resistance Stage of lactation was categorized as early (1 up to 4 from prolonged and indiscriminate usage of some months), mid (4 up to 8 month), and late (8 month up antimicrobials. to the beginning of dry period) and hygiene of udder In west Hararghe Zone, famers reported mastitis as was categorized as Washing/drying, Washing only and one of the health problems among dairy cattle. not at all (Berhanu et al., 2010). In the study area, dairy However, to the best of our knowledge, a systematic cattle are managed under semi- intensive management study was not conducted to provide detailed system and provided natural pasture and agricultural by information on cattle mastitis. Thus, the study was product. conducted to estimate the prevalence of bovine mastitis, assess risk factors, isolate and identify the Study Design bacterial causative agents, and determine the drug A cross-sectional study was conducted from October resistance patters of the isolated bacteria in the study 2009 to March 2010 at cow and quarter level based on area. clinical and subclinical mastitis and indirect test (California mastitis test and culture) for subclinical Materials and Methods mastitis, microbial isolation and in-vitro antimicrobial Study Areas susceptibility test. The study was conducted in west Hararghe (latitude: 7°50’–9°50’ N; longitude: 40°00’–41°25’ E; altitude: Sampling and Sample Size Determination 1200–3060 m) administrative zones which are located For estimation of the prevalence of mastitis in the in the eastern part of Oromia Regional State and share study area, the sample size was determined by assuming boundaries with Afar Regional State, Somali Regional the expected prevalence to be 50% with the 95% State, as well as the east Hararghe Zone. The livestock confidence level and desired precision of 5% using the population of west Hararghe is 1,149,089 cattle, formula described by Thrusfield (2005). Accordingly, 510,164 sheep and goats (WHZBA, 2006). It has three the minimum sample size required from each of the distinct agro-ecologies and different farming system five districts was 384 but only a total of 1019 cows that consists of highland (17.5%), mid highland were taken since the study was conducted in dry season (28.5%), and lowland (54.0%) and have two rainy in May and June and some of the areas were not seasons, the short rainy season and the main rainy accessible due to lack of transportation. The rural season, with a mean annual rainfall ranging from below kebeles, villages and lactating cows were also selected 700 mm in the lowlands to nearly 1200 mm at higher based on their accessibility to transportation. altitudes. Most of the people living in Hararghe lowlands are nomadic agro-pastoralists who move their Study Methodology livestock seasonally, following grazing opportunities Milk sampling procedure: History of the selected and water availability (Guinand, 2000). milking cow was taken to record information such as number of parturitions, parity, treatment, and physical Study Animals examination of the udder to determine blind teats and The study was conducted in districts that have major other defects and inflammation. The milk samples were towns with significant milk flow in the operational area taken from cows that are not treated with either intra- of Hirna Regional Veterinary Laboratory. Lactating mammary or systematic antimicrobials agents. The cows of local breed 15 days after parturition were udder was cleaned with warm water, antiseptics and selected for the study. The lactating cows were selected dried with clean towel.